Configuring perimeter of balloon electrode as location sensor

ABSTRACT

An expandable balloon, which is coupled to a distal end of a shaft for insertion into an organ of a patient, includes an expandable membrane, one or more electrodes and one or more respective conductive coils. The one or more electrodes are disposed over an external surface of the membrane. The one or more respective conductive coils are each disposed proximate a respective RF ablation electrode. The one or more conductive coils are configured as magnetic sensors.

FIELD OF THE INVENTION

The present invention relates generally to tracking a probe within aliving body, and specifically to magnetic-based measurements.

BACKGROUND OF THE INVENTION

Intrabody probes, such as catheters, may include position sensors attheir distal ends. For example, U.S. Patent Application Publication2002/0087156 describes a method for attaching a sensor to an inflatableballoon. The method is particularly useful in the construction of atissue ablation catheter for forming a lesion along a substantiallycircumferential region of tissue wherein a sensor is used for monitoringthe temperature of the tissue being ablated. In an embodiment, one ormore position sensor elements (not shown) are located in, or near, theexpandable member. A circumferential ablation member with the ablationelement that forms an ablative circumferential band that circumscribesan expandable member embodied as a balloon. In a sequential mode ofoperation for the ablation member, the position sensor of the positionmonitoring assembly may be coupled to the expandable member.

As another example, U.S. Pat. No. 6,574,492 describes a catheter formeasuring physiological signals in a heart comprises a structure at adistal end of the catheter wherein the structure has a plurality ofarms, an electrode fixed to each arm and a device for generatingposition information located on each arm. The arms are located near thelong axis of the catheter during insertion of the catheter within aheart and the arms are spreadable apart and away from the long axis ofthe catheter when the structure is within the heart. In a preferredembodiment of the invention, a position sensor having one or more coilsis embedded in a lobe, preferably near an electrical sensor, so as tomore exactly determine the relative position of the electrical sensor.

U.S. Patent Application Publication 2014/0364848 describes a system fordiagnosis or treatment of tissue in a body. The system includes anablation catheter having an ablation delivery member disposed proximatea distal end of a shaft of the catheter and configured to deliverablation energy to ablate the tissue. In one embodiment, the ablationdelivery member comprises an ablation electrode and may also beconfigured to generate a signal indicative of electrical activity in thetissue. The catheter further includes one or more sensing electrodesdisposed proximate the ablation delivery member. The sensing electrodesare configured to generate signals indicative of electrical activity inthe tissue. In an embodiment, the sensing electrodes function asposition sensors.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides an expandable ballooncoupled to a distal end of a shaft for insertion into an organ of apatient. The expandable balloon includes an expandable membrane, one ormore electrodes and one or more respective conductive coils. The one ormore electrodes are disposed over an external surface of the membrane.The one or more respective conductive coils are each disposed proximatea respective RF ablation electrode. The one or more conductive coils areconfigured as magnetic sensors.

In some embodiments, the expandable balloon further includes one or morerespective leads, each configured to provide a common electrical contactfor an electrode and for a coil wound around the electrode.

In some embodiments, the conductive coil is disposed on a flexibleprinted board (PBC), and wherein the flexible PCB is attached to theexpandable membrane.

In an embodiment, the one or more electrodes are radiofrequency (RF)ablation electrodes. In an alternative embodiment, the one or moreelectrodes are sensing electrodes to sense signals produced by cardiactissues.

There is additionally provided, in accordance with an embodiment of thepresent invention, a system including an expandable balloon and aprocessor. The expandable balloon is coupled to a distal end of a shaftfor insertion into an organ of a patient, wherein the expandable balloonincludes an expandable membrane, one or more electrodes, and one or morerespective conductive coils. The one or more electrodes are disposedover an external surface of the membrane. The one or more respectiveconductive coils are each disposed proximate a respective RF ablationelectrode, wherein the one or more conductive coils are configured asmagnetic sensors. The processor is configured to, based on signalsreceived from the one or more conductive coils, estimate a spatialconfiguration of the expandable balloon inside the organ.

In some embodiments, the processor is configured to estimate the spatialconfiguration of the expandable balloon by estimating a location of theballoon inside the organ.

In some embodiments, the processor is configured to estimate the spatialconfiguration of the expandable balloon by estimating an orientation ofthe balloon inside the organ.

In an embodiment, the processor is configured to estimate theorientation by estimating at least one of a deflection of the balloonrelative to a longitudinal axis defined by the distal end of the shaftand a roll angle about the longitudinal axis.

In another embodiment, the processor is configured to estimate thespatial configuration of the expandable balloon by estimating a shape ofthe balloon inside the organ.

In some embodiments, the processor is configured to estimate the shapeby identifying an extent of expansion of the balloon.

In an embodiment, the processor is configured to estimate the shape bydetecting whether the balloon is fully expanded or not.

There is further provided, in accordance with an embodiment of thepresent invention, a method, including irradiating one or more magneticfields in a body of a patient. Signals resulting from the generatedmagnetic fields are generated by one or more conductive coils that aredisposed proximate each electrode disposed over an external surface of amembrane of an expandable balloon coupled to a distal end of a shaftinserted in an organ of the patient. Based on the generated signals, aspatial configuration of the expandable balloon inside the organ isestimated using a magnetic tracking system.

There is furthermore provided, in accordance with an embodiment of thepresent invention, a manufacturing method, including disposing one ormore electrodes over an external surface of a membrane of an expandableballoon for insertion into an organ of a patient. a respectiveconductive coil is wound around a perimeter of each electrode, whereinthe conductive coil is configured as a magnetic sensor.

The present invention will be more fully understood from the followingdetailed description of the embodiments thereof, taken together with thedrawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic pictorial illustration of a catheter-basedposition tracking and ablation system comprising a balloon catheter, inaccordance with an embodiment of the present invention;

FIG. 2 is a schematic pictorial illustration of the balloon catheter ofFIG. 1 comprising one or more coil sensors, in accordance with anembodiment of the present invention;

FIG. 3 is a schematic diagram of an electrical connection scheme of theablation electrode and the coil sensor of FIG. 2 , in accordance with anembodiment of the present invention; and

FIG. 4 is a flow chart that schematically illustrates a method andalgorithm for tracking the expandable balloon of FIG. 2 using one ormore coil sensors, in accordance with an embodiment of the presentinvention; and

FIG. 5 is a flow chart that schematically illustrates a method andalgorithm for estimating a spatial configuration of the expandableballoon of FIG. 2 , in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS Overview

A balloon catheter typically comprises an expandable balloon that iscoupled to a distal end of a shaft for insertion into a cavity of anorgan of a patient. For the best outcome of a balloon treatment, aphysician may need to determine an exact location, orientation and shapeof the balloon inside the organ. For example, in a balloon ablationprocedure performed inside the left atrium of the heart, the physicianmay need to know the exact location and orientation of the balloonrelative to an opening of a pulmonary vein so as to evenly ablate tissueover an entire circumference of the opening.

In the context of this disclosure, the term “balloon location andorientation” refers to either or both of (i) a location plus directionin space of the longitudinal axis defined by a distal end of the shaft,and (ii) a location plus tilt or deflection of the balloon relative tothe longitudinal axis. When the expanded balloon is free of constraintsthe surface of the balloon revolves around a direction parallel to thelongitudinal axis. In such case, ablation elements, such as electrodes,which lay on an equator of the balloon (the equator defining a planeperpendicular to the direction of the balloon) are aligned perpendicularto the longitudinal axis.

However, when the balloon is constrained and/or deflected upon contactwith cavity wall tissue, the balloon direction is not necessarilyparallel to the longitudinal axis. As a result, the ablation electrodesare tilted at some unknown angle. For example, the electrodes may betilted relative to an opening of the pulmonary vein to be ablated by theelectrodes, resulting in uneven ablation.

Embodiments of the present invention that are described hereinafterprovide an expandable radiofrequency balloon catheter comprising one ormore magnetic sensors, such as single-axis magnetic sensors, each ofembodied as a conductive coil wound around a respective electrodedisposed over an external surface of the expandable membrane of theballoon. In some embodiments, the electrode is an RF ablation electrode.Using the disclosed sensors, a processor of a magnetic tracking systemestimates a spatial configuration of the balloon inside the organ,comprising a location and/or orientation and/or shape of the balloon,accurately enough in demanding clinical applications, as describedbelow.

Additionally or alternatively, the processor may be configured toestimate at least one of a deflection of the balloon relative to alongitudinal axis defined by the distal end of the shaft and a rollangle (i.e., rotation angle) about the longitudinal axis. Theseparameters are also considered examples of the “spatial configuration”of the balloon. In this way, the physician can advance the balloon totarget tissue otherwise difficult to access, and only then expand theballoon. After the balloon is fully expanded, the magnetic positionsystem, using the disclosed coils, is capable of tracking the balloonlocation and/or direction even if the balloon is constrained and/ordeflected relative to a longitudinal axis defined by a distal end of ashaft.

In some embodiments, the spatial configuration of the expandable balloonfurther comprises a shape of the balloon inside the organ. The processormay estimate the shape, for example, by identifying an extent ofexpansion of the balloon. In an embodiment, the processor is configuredto estimate the shape by detecting whether the balloon is fully expandedor not. In some embodiments, using the disclosed coil sensors thephysician can determine the balloon orientation even when the balloon isonly partially expanded (e.g. partially inflated).

Typically, with multiple RF ablation electrodes disposed over themembrane, multiple respective magnetic sensors can be disposed over anentire circumference of the expandable balloon. In some embodiments, thedisclosed coil encompasses an area approximately equal to that of theablation electrode, which is sufficient, for a coil with severalwindings around the electrode perimeter, to generate a location signal.Typically, each winding width is several tens of microns, so that theoverall width of the perimeter is kept below half a millimeter.

In some embodiments, a single lead is used to electrically connect boththe ablation electrode and the wound coil to respective interfaces ofthe system (i.e., a single lead, which is configured to provide a commonelectrical contact to an RF ablation electrode and the coil wound aroundthe RF ablation electrode), so only one additional lead is required forthe coil (i.e., to close a circuit by connecting the other end of thecoil). In some embodiments, the ablation electrode is separated into twoor more sub-electrodes, and both of the leads to the ablation electrodeare used to connect to the coil, so that no extra leads are required.

Typically, the processor is programmed in software containing aparticular algorithm that enables the processor to conduct each of theprocessor-related steps and functions outlined hereinafter.

The ability to estimate the shape of the balloon is enabled, forexample, by the fact that the coils (the position sensors) are fitted onthe membrane, away from the longitudinal axis of the catheter. Byproviding magnetic tracking capabilities of balloon position,orientation and shape as described above, embodiments of the presentinvention enable a physician operating the balloon catheter to align theballoon inside a cavity relative to target tissue, so as for example, touniformly ablate tissue.

Furthermore, the disclosed coils may eliminate the need to incorporateadditional means for tracking the balloon catheter position andorientation. For example, the disclosed technique may enable providing a“smooth” balloon, by eliminating the need to fit an additional positionand/or orientation sensing element at a protruding distal edge of theballoon catheter.

System Description

FIG. 1 is a schematic pictorial illustration of a catheter-basedposition tracking and ablation system 20 comprising a balloon catheter40, in accordance with an embodiment of the present invention. System 20is used to determine the position and direction of balloon catheter 40,seen in an inset 25 coupled to a distal end of a shaft 22. System 20 isfurther used for providing information regarding the balloon state ofinflation (e.g., if balloon 40 is fully expanded). Typically, ballooncatheter 40 is used for therapeutic treatment, such as spatiallyablating cardiac tissue, for example at the left atrium.

Physician 30 navigates balloon catheter 40 to a target location in aheart 26 of a patient 28 by manipulating shaft 22 using a manipulator 32near the proximal end of the catheter and/or deflection from a sheath23. Balloon catheter 40 is inserted, in a folded configuration, throughsheath 23, and only after the balloon is retracted from the sheath 23does balloon catheter 40 regain its intended functional shape. Bycontaining balloon catheter 40 in a folded configuration, sheath 23 alsoserves to minimize vascular trauma on its way to the target location.

For position and direction measurements, balloon catheter 40incorporates conductive coils 50, which are disposed on an outer surfaceof the balloon membrane 44 and are used as magnetic position sensors, asdescribed below. Each coil is wound around a perimeter of aradiofrequency (RF) ablation electrode 51, where the ablation electrodeand the coil share an electrical lead, and are both connected by wiresrunning through shaft 22 to interface circuits 44 in a console 24. Adetailed view of coil 50 wound around the perimeter of ablationelectrode 51, where both are disposed over membrane 44, is shown ininset 35 of FIG. 2 .

Console 24 comprises a processor 41, typically a general-purposecomputer and a suitable front end and interface circuits 44 fortransmitting and receiving signals, such as RF signals and positionsignals, respectively. Interface circuits 44 may receiveelectrocardiograms from surface electrodes 49, which are seen in theexemplified system as attached by wires running through a cable 39 tothe chest and to the back of patient 28.

Console 24 comprises a magnetic-sensing sub-system. Patient 28 is placedin a magnetic field generated by a pad containing magnetic fieldradiators 42, which are driven by unit 43. The magnetic fieldsirradiated by radiators 42 generate signals in coils 50, which are thenprovided as corresponding electrical inputs to processor 41, which usesthe generated signals to calculate a position and/or direction ofballoon catheter 40.

The method of position sensing using external magnetic fields isimplemented in various medical applications, for example, in the CARTO™system, produced by Biosense Webster Inc., and is described in detail inU.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612 and6,332,089, in PCT Patent Publication WO 96/05768, and in U.S. PatentApplication Publications 2002/0065455 A1, 2003/0120150 A1 and2004/0068178 A1, whose disclosures are all incorporated herein byreference.

Processor 41 is typically programmed in a suitable software code tocarry out the functions described herein. The software may be downloadedto the computer in electronic form, over a network, for example, or itmay, alternatively or additionally, be provided and/or stored onnon-transitory tangible media, such as magnetic, optical, or electronicmemory. In particular, processor 41 runs a dedicated algorithm asdisclosed herein, including in FIG. 4 , that enables processor 41 toperform the disclosed steps, as further described below.

FIG. 1 shows only elements related to the disclosed techniques, for thesake of simplicity and clarity. System 20 typically comprises additionalmodules and elements that are not directly related to the disclosedtechniques, and thus are intentionally omitted from FIG. 1 and from thecorresponding description.

Configuring Perimeter of Balloon Electrode as Location Sensor

FIG. 2 is a schematic pictorial illustration of balloon catheter 40 ofFIG. 1 comprising one or more coil sensors 50, in accordance with anembodiment of the present invention. As seen, balloon 40 is coupled tothe distal end of shaft 22 that defines a longitudinal axis 58. Ballooncatheter 40 comprises RF ablation electrodes 51 that are evenly disposedover an equator 48 of expandable membrane 44. Each coil 50 is woundaround the perimeter of each RF ablation electrode 51. As further seen,balloon catheter 40 is free of constraints, and thus equator 48 lies ina plane perpendicular to longitudinal axis 58.

In an embodiment, coil 50 is disposed on a flexible printed circuitboard (PCB) 53, and flexible PCB 53 is attached to expandable membrane44. In some embodiments coil 50 is made of a wire wound and encapsulatedover to the flexible PCB. In another embodiment, coil 50 is patterned(e.g., printed) over flexible PCB 53.

Inset 45 shows balloon catheter 40 in two directions, the “free”direction parallel to axis 58, and a “deflected” direction 58′. As seen,when the balloon is deflected, for example, due to contact with walltissue, the center location of the balloon changes from a location 47 toa deflected location 47′. Moreover, equator 48 is deflected to anequator 48′, which means that electrodes 51 are aligned around the newdirection 58′. Location 47′ and direction 58′ can be tracked using thedisclosed coil sensors disposed over membrane 44, as described below. Insome embodiments, based on signals from the coil sensors, processor 41estimates a roll angle 59 of balloon catheter 40 around axis 58.

FIG. 2 shows that each RF ablation electrode 51 and a respective coil 50share a lead 55, as further described below. In an embodiment, shown ininset 35, each coil 50 is made of several turns 52 (i.e., windings 52).Each turn 52 of coil 50 has a width of several tens of microns, so thatthe overall width 54 of the perimeter (i.e., of coil 50) is kept to nomore of several hundred microns. Each ablation electrode has an area ofseveral tens of mm2, so that a coil wound several turns around theelectrode perimeter has an effective area of several hundred mm2, whichis sufficient for generating the required signal. A typical width of aturn on coil 50 is about 40-50 microns, so six or seven turns results inan effective area of about 250-350 mm2.

The illustration shown in FIG. 2 is chosen purely for the sake ofconceptual clarity. Other geometries of ablation electrodes arepossible. Elements which are not relevant to the disclosed embodimentsof the invention, such as irrigation ports and temperature sensors, areomitted for the sake of clarity.

FIG. 3 is a schematic diagram of an electrical connection scheme of RFablation electrode 51 and coil sensor 50 of FIG. 2 , in accordance withan embodiment of the present invention. The content of frame 40 aschematically shows the disclosed electrical circuit formed with eachablation electrode 51 (represented by a resistor 51 a), and the woundcoil 50 (represented by a coil 50 a). As seen, coil 50 a shares a lead55 with resistor 51 a, wherein coil 50 a generates a tracking signali_(Signal).

Signals generated by coil 50 a are transmitted using lead 55 andsubsequently by a wire in shaft 22 (not shown) to electrical readoutcircuitry 44 c included in interface circuits 44 inside console 24,schematically shown by a frame 44 a. An RF source 43 c to electrode 51 ais also seen inside frame 44 a. Using a single lead 55 to connect bothcoil 50 a and resistor 51 a (i.e., RF ablation electrode 51) tointerface circuits 44 saves separate dedicated wiring.

The schematic diagram shown in FIG. 3 is chosen purely for the sake ofconceptual clarity. Other connection schemes that utilize a shared lead,such as a lead shared as a common electrical ground, are possible. In anembodiment, coil 50 may be connected via a reinforced isolated amplifierthat converts the generated signal from a high-voltage domain to alow-voltage domain. Additional elements may be used as well, such aselectronic demodulation circuits.

FIG. 4 is a flow chart that schematically illustrates a method andalgorithm for tracking the expandable balloon of FIG. 2 using one ormore coil sensors, in accordance with an embodiment of the presentinvention. The algorithm of FIG. 4 ensures that one skilled in thecomputer art can generate the necessary software code, as well as anyother needed auxiliary steps, for a general-purpose computer to carryout the specific purposes of tracking the location or shapes of theexpandable balloon of FIG. 2 . The algorithm according to the presentembodiment carries out a process that begins with physician 30positioning a partially expanded balloon catheter 40 at a targetlocation inside a cardiac cavity of heart 26, such as at an ostium of apulmonary vein, at a balloon positioning step 70. Next, at a balloontracking step 72, system 20 uses coils 50 to measure a position and anorientation of balloon catheter 40, e.g., relative to a given crosssection (i.e., slice) of the ostium. Next, physician 30 decides if thepartially expanded balloon catheter 40 is aligned correctly relative tothe ostium, at a decision step 74.

If physician 30 finds that balloon catheter 40 is well aligned, thenphysician 30 fully inflates the balloon and performs a treatment, suchas an RF ablation, in an RF balloon treatment step 76.

FIG. 5 is a flow chart that schematically illustrates a method andalgorithm for estimating a spatial configuration of the expandableballoon of FIG. 2 , in accordance with an embodiment of the presentinvention. By virtue of the embodiments described herein, we havedevised an algorithm, as shown in FIG. 5 , for determining locations aswell as other operational parameters of a balloon catheter while theballoon is located within biological tissues. In particular, the methodcan be achieved with the following algorithm exemplified in FIG. 5 :irradiating (80) one or more magnetic fields inside an organ of apatient, and generating (82) signals resulting from the generatedmagnetic fields. The signals are generated by one or more conductivecoils from the magnetic fields irradiating upon the coils, each of whichis disposed proximate each electrode disposed over an external surfaceof a membrane of an expandable balloon coupled to a distal end of ashaft inserted in an organ of the patient. The step continues with usinga magnetic tracking system, based on the generated signals andestimating (84) a spatial configuration of the expandable balloon insidethe organ. It is noted that the estimating may include estimating one ormore of the following: estimating the location of the balloon inside theorgan, estimating the orientation of the balloon inside the organ,estimating at least one of a deflection of the balloon relative to alongitudinal axis defined by the distal end of the shaft and a rollangle about the longitudinal axis, and estimating a shape of the ballooninside the organ. The step of estimating a shape may include identifyingan extent of expansion of the balloon or detecting whether the balloonis fully expanded or not.

The example flow chart shown in FIG. 4 is chosen purely for the sake ofconceptual clarity. The present embodiment also comprises additionalsteps of the algorithm, such as acquiring intra-cardiacelectrocardiograms, which have been omitted from the disclosure hereinpurposely in order to provide a more simplified flow chart given thatone skilled in this art has the requisite background knowledge forprogramming such algorithm in the field of electrophysiology. Inaddition, other steps, such as temperature measurements and applyingirrigation, are omitted for clarity of presentation.

Although the embodiments described herein mainly address cardiacapplications, the methods and systems described herein can also be usedin other applications, such as in otolaryngology, neurology, cardiology,blood vessel treatment and renal denervation.

It will thus be appreciated that the embodiments described above arecited by way of example, and that the present invention is not limitedto what has been particularly shown and described hereinabove. Forexample, cardiac signal sensing electrodes can be utilized in place ofthe ablation electrodes or a combination of both signal-sensingelectrodes and ablation electrodes can be utilized. Rather, the scope ofthe present invention includes both combinations and sub-combinations ofthe various features described hereinabove, as well as variations andmodifications thereof which would occur to persons skilled in the artupon reading the foregoing description and which are not disclosed inthe prior art. Documents incorporated by reference in the present patentapplication are to be considered an integral part of the applicationexcept that to the extent any terms are defined in these incorporateddocuments in a manner that conflicts with the definitions madeexplicitly or implicitly in the present specification, only thedefinitions in the present specification should be considered.

The invention claimed is:
 1. An expandable balloon coupled to a distalend of a shaft for insertion into an organ of a patient, the expandableballoon comprising: (a) an expandable membrane; (b) one or moreelectrodes disposed over an external surface of the membrane; and (c)one or more respective conductive coils, each conductive coil woundseveral turns around an entirety of a perimeter of a respectiveelectrode, the one or more conductive coils are being configured asmagnetic sensors.
 2. The expandable balloon according to claim 1, andfurther comprising one or more respective leads, each configured toprovide a common electrical contact for an electrode and for a coilwound around a perimeter of the electrode.
 3. The expandable balloonaccording to claim 1, the conductive coil is being disposed on aflexible printed board (PBC), and the flexible PCB is being attached tothe expandable membrane.
 4. The expandable balloon according to claim 1,the one or more electrodes are being radiofrequency (RF) ablationelectrodes.
 5. The expandable balloon according to claim 1, the one ormore electrodes is being selected from a group of electrodes consistingof ablation electrodes, sensing electrodes or combinations thereof.
 6. Asystem, comprising: (a) an expandable balloon coupled to a distal end ofa shaft for insertion into an organ of a patient, the expandable ballooncomprising: (i) an expandable membrane; (ii) one or more electrodesdisposed over an external surface of the membrane; and (iii) one or morerespective conductive coils, each conductive coil wound several turnsaround a perimeter of a respective electrode such that each conductivecoil encircles the respective electrode, the one or more conductivecoils being configured as magnetic sensors; and (b) a processor, whichis configured to, based on signals received from the one or moreconductive coils, estimate a spatial configuration of the expandableballoon inside the organ.
 7. The system according to claim 6, theexpandable balloon further comprising one or more respective leads, eachconfigured to provide a common electrical contact for an electrode andfor the conductive coil wound around a perimeter of the electrode. 8.The system according to claim 6, the conductive coil is being disposedon a flexible printed board (PBC), and the flexible PCB being attachedto the expandable membrane.
 9. The system according to claim 6, theprocessor is being configured to estimate the spatial configuration ofthe expandable balloon by estimating a location of the balloon insidethe organ.
 10. The system according to claim 6, the processor is beingconfigured to estimate the spatial configuration of the expandableballoon by estimating an orientation of the balloon inside the organ.11. The system according to claim 6, the processor is being configuredto estimate the orientation by estimating at least one of a deflectionof the balloon relative to a longitudinal axis defined by the distal endof the shaft and a roll angle about the longitudinal axis.
 12. Thesystem according to claim 6, the processor is being configured toestimate the spatial configuration of the expandable balloon byestimating a shape of the balloon inside the organ.
 13. The systemaccording to claim 12, the processor is being configured to estimate theshape by identifying an extent of expansion of the balloon.
 14. Thesystem according to claim 12, the processor is being configured toestimate the shape by detecting whether the balloon is fully expanded ornot.
 15. A catheter for electrophysiology applications, comprising: (a)a shaft having a distal end; and (b) an end effector coupled to thedistal end of the shaft, the end effector including: (i) an expandablemembrane having an outer surface, (ii) an electrode secured to the outersurface of the membrane, and (iii) a position sensor secured to theouter surface of the membrane, the position sensor including a coilhaving a plurality of windings extending around an entire perimeter ofthe electrode.
 16. The catheter of claim 15, the end effector furthercomprising an electrical lead electrically coupled to each of theelectrode and the position sensor.
 17. The catheter of claim 16, theelectrode including an ablation electrode.
 18. The catheter of claim 16,further comprising a wire electrically coupled to the electrical lead,the wire extending along the shaft.
 19. A system comprising: (a) thecatheter of claim 18; and (b) a processor electrically coupled to thewire, the wire and the electrical lead being configured to transmitsignals generated by the position sensor to the processor.
 20. An endeffector of a catheter, the end effector comprising: (a) an expandablemembrane having an outer surface; (b) an electrode secured to the outersurface of the membrane; and (c) a position sensor secured to the outersurface of the membrane, the position sensor including a coil having aplurality of windings extending around a perimeter of the electrode suchthat the coil surrounds the electrode.
 21. The end effector of claim 20,further comprising an electrical lead electrically coupled to each ofthe electrode and the position sensor.
 22. The end effector of claim 21,the electrode including an ablation electrode.
 23. A system comprising:(a) the end effector of claim 22; and (b) a processor electricallycoupled to the electrical lead via a wire, the wire and the electricallead being configured to transmit signals generated by the positionsensor to the processor.